Electric gaseous discharge device



May 18, 1937. A.' BUNGER ET AL 2, 8

7 ELECTRIC GASEOUS DISCHARGE DEVICE v v Filed July 7, 193a r YINVENTORSAlberl: Burge KuHr Larcke gur' wiegjdnd.

ATTQRNEY "Patented May 18, 1937 UNITED STATES Neuendorf, Germanydassigno'rs to- General Electric Company, a corporation of New YorkApplication July 7,1936, Serial No. 89,412

I In Germany July 27, 1935 4 Claims. (01. l76-124) The present inventionrelates to electric gase ous discharge devices, and in particular tovapor are devices operating with a high vapor density.

A particular object of the invention is to reduce the time delay beforea discharge in such a device can be restarted at the usual appliedpotential. A further object of the invention is to provide cooling meansfor such a device. Still another object of the invention is to provide anovel regulation of the cooling in accordance with the operation of thedischarge device. Still other objects and advantages of the inventionwill appear from the following detailed specification or from aninspection of the accompanying drawing.

The invention consists in the new and novel combination of elementshereinafter set forth and claimed.

During the operation of vapor discharge devices, such as the highintensity mercury vapor arc lamp, the vapor density therein is raised toa relatively high value, as is well known, in order to attain thedesired constricted discharge and high efficiency operation. As a resultof this high density of the vapor the potential required to restart thelamp immediately after extinction of a discharge therein is extremelyhigh, far in excess of that required when the device is at roomtemperature. The applied potential is ordinarily insufficient to restartthe discharge under these conditions and hence the lamp remainsextinguished, even though potential be applied thereto, until the lamphas cooled to such anextent that the discharge can be restarted on thethe applied potential. This cooling period with the usual high intensitymercury vapor arc lamps amounts to from 2 ,to 10 minutes, depending upontheir size, ambient temperature and the type of enclosure.

We have now found that this cooling time is materially shortened by anovel arrangement of our invention, wherein an electrically driven fanor blower is connected in parallel with the discharge device. With thisnovel arrangement the potential between the terminals of the dischargedevice is applied to the fan motor and determines the speed thereof.Thus at starting the discharge potential in a mercury vapor arc lamp ofthe high intensity type which is now going into extensive useis of theorder of to 40 volts, and at this potential the fan will be rotated onlyslowly, if at all. During,continued operation the vapor density of thelamp increases. and the discharge voltage increases therewith to apotential of the order of 150 volts, whereupon the fan motor speeds up.The fan is still not particularly effec ivea th p d; however, andresults o'nly'in a'steady moderate cooling whichserves toprotect thelamp against 5 excessive temperature rises. As soon as the discharge hasbeen momentarily extinguished, how ever, it will not restart attheapplied potential,

' and hence practically the full 220 volt s which.

is usually applied to these" devices is impressed 10 across theterminalsofthe lamp, andlikewise across the fan motor, the current drawnby the fan motor producing but little voltage drop in the usualseries'impedance. The fan is there? upon operated at full speed and thusrapidly l5 cools the discharge' tube to atemperature at which thedischarge willagain-start on the ap pliedpotential. As soon asthe lampisthus restarted the speed of the fan motor is again drastically reduced,and the operation thereof 20 continues in the mannerhereinbeforedescribed for normal operation of the lamp.

Since the potential required .to restart the lamp is determined bythecoldest spot on the lamp envelope, however. small, it is desirable toconfine the cooling of the lamp to a small por-, tion thereof, so thatthe entire vessel will regain its operating temperature. asflsoon aspossible after the dischargeihas been restarted. For this purpose thedraft of the fan or blower is usually directed at a single spoton thelamp envelope,

preferably some point away from the electrodes,

and where desired heat insulating means are provided on the portions ofthe envelope adjacent the electrodes in order to keep the electrodes ashot as possible during the cooling period.

In some cases a special switching arrangement, including a delayedopening switch, is provided whereby the. fan motor iscaused to operatefor a predetermined period after every extinguishment of the lamp, so asto insure rapid restarting of the lamp should its light be againdesired. within a few minutes. I

For the purpose of illustrating our invention we have shown twoembodiments thereof in the accompanying drawing in'which v Fig. 1schematically shows the connection of the fan motor in the circuit of ahigh intensity mercury vapor arc lamp to produce the desired cooling,and i Fig. 2 shows a modification of the circuit of Fig. 1.

In this drawing, with particular reference to Fig. 1, there is shown ahigh intensity mercury vapor arc lamp I of any usual type containing theusual gas and mercury filling. and having thermionic electrodes. Thislamp isconnecte'd in series through an inductance 2, which serves tostabilize the discharge, and switch 3 across the inserted between theterminal I of the lamp I and the connection point 8 to the fan motor,

whereby the lamp can be extinguished without interrupting the operationof the fan motor.

In the operation of this device, switch 9 being closed, the lamp isstarted into operation byclosing' the switch 3, the cold lamp having astarting potential below that applied. The lamp voltage immediatelyfalls to from 20 to 40-volts, and hence the voltage applied to the motorof the fan 6 is thus so lowthat this motor either idles along or failsto operate at all. As'the temperature of the lamp increases the voltagedrop therein likewise increases to the normal operating voltage of theorder of 150 volts, with a resultant moderate speeding up of the fan;The cooling produced thereby is still relatively small, however, andserves only to protect the lamp against an excessive temperature rise;If the lamp is now extinguished by opening the switch 3 and directlyafterward, for example one second later, the

.switch is again closed, the lamp will not restart at the appliedpotential due to the high vapor density existing within the lamp at thenormal operating temperature. Heretofore, it has been necessary to awaitthe natural cooling of the lamp beforethe'flanifctiuld be restarted, butwith our rinew arrangement the fan 6 is operated at this time at fullspeed since the entire line voltage, with the, exception of therelatively small voltage drop in the inductance 2 as a result of themotor current, is impressed upon the fan motor. As a result the lamp,and particularly a small area near the center thereof, is rapidly cooledto the temperature at which'the lamp will again start on the appliedpotential. As soon as the lamp restarts the voltage across the fan motoris'of course, drastically reduced,so that the fan again rotates at agreatly reduced speed.

The lamp I can also be extinguished by opening the switch 9, in whichcase the fan 6 continues to operate at full speed, rapidly cooling thelamp I, until the switch 3 is opened at some later time. In this mannerprovision is made to restart the lamp as soon as possible after it isits light is again position the line terminal is connected over thecontact I3 with the lamp I and also over the contact l2 with the'motorof the fan 6; the otherlineterminal 4"is connected over the con-2,oso,9oa i I ftact II with both the lamp and the fan motor through theinductance 2. In this position of the switch I D it is therefore obviousthat the lamp I and the fan 6 are connected in parallel, this 'beingtheposition of the switch for operation of the lamp. In order to extinguishthe lamp the switch III is moved to its other work position.

In' this position the line terminals 4 and 5 are connected with thecontacts I I', I2 which lead to the fan motor over the conductors I4,I5, the time-switch I6 and the conductors I4, I5. The time switch I8 isso constructed that after an adjus'table time, for example 2 minutes, itdisconnects the fan 6 from the supply line.

With this arrangement when the lamp I is extinguished by operation ofthe switch III the fan 6 issimultaneously connected directly to the lineand thus left in full operation for the period determined'by the timeswitch I G, with the result that the lamp is rapidly cooled off and willimmediately restart if the light of the lamp is again desired after evena brief interval.

While we have described our invention by reference to certain specificembodiments thereof it' is to be understood that it is not limitedthereto but that various changes, omissions and substitutions, withinthe scope of the appended claims, may be made therein without departingfrom the spirit thereof.

What we claim as new and desire .to secure by Letters Patentof theUnited States, is:

1. In combination, a vapor discharge device of the high intensity'typeand a fan arranged to direct a blast of air upon said lamp, the motorfor said fan being connected in parallel with said discharge device,whereby the cooling effect of said fanis determined by the condition ofsaid discharge device. v

2. In combination, a vapor discharge .device of the high intensity type,a fan so disposed with respect to said device that it selectively coolsthe central portion thereof, the motor for said fan being connected inparallel with said discharge device, whereby the cooling effect of saidfan is determined by the condition of said discharge device.

. 3. In combination, a vapor discharge device of the high intensitytype, a fan arranged to direct a blast of air upon said lamp, the motorfor said fan being connected in parallel with said dis-'- charge device,whereby the cooling effect of said .fan is determined by the conditionof said discharge device, and means to open the circuit through saidlamp without opening the circuit through said motor.

4. In combination, a vapor discharge device of the high intensity type,a fan arranged to direct a blast of'air upon said lamp, the motor forsaid fan being connected in parallel with said discharge device, wherebythe cooling efiect of said fan is determined by the condition of saiddischarge device, means to open the circuit through said device, andmeans including a delayed opening switch to continue the operation ofsaid fan for a predetermined period after the circuit through saiddevice has been opened.

- ALBERT BUNGER.

KURT LARCHE. KURT WIEGAND.

